I. Field of the Invention
This invention relates to compositions and to processes for controlling the gelation time of alkali metal silicate-containing compositions. More specifically, it relates to compositions and processes for controlling the gelation time of alkali metal silicate-containing compositions useful for stabilizing soil by incorporating therein certain polyhydroxy compounds which modify the gel time of the silicate compositions, whereby homogeneous gelled compositions of good load bearing capacity can be prepared even at elevated temperatures, e.g., 100.degree. F. or higher.
II. Description of the Prior Art
It has long been known to produce gelled, cement-like masses from aqueous solutions of alkali metal silicates by the addition of salts of metals other than alkali metals, e.g., aluminum or iron. It is further known, as set forth in U.S. Pat. No. 2,968,572 (Peeler), to render soil impermeable to fluid and/or to strengthen it by injecting into said soil a composition comprising an aqueous alkali metal, e.g., sodium silicate and a soluble amide such as formamide, acetamide, propionamide, butyramide and the like. During gelation of such compositions and thereafter, however, gaseous ammonia is liberated by the silicate-amide reaction, constituting a hazard to those working nearby, particularly in confined areas.
The alkali metal silicate-containing soil stabilizing compositions described and claimed in U.S. Pat. No. 3,306,758 (Miller), issued Feb. 28, 1967, represents an improvement over the invention set forth in the aforesaid U.S. Pat. No. 2,968,572, in that a lower alkyl aldehyde, e.g., formaldehyde, acetaldehyde and the like, is incorporated into the silicate-amide mixture as a binding or complexing agent for the ammonia generated during the gelling reaction. Thus, no significant quantities of ammonia vapors are released upon applying and reacting the silicate and amide components.
U.S. Pat. No. 3,028,340 (Gandon et al.), issued Apr. 3, 1962, describes and claims a composition suitable for soil stabilization comprising an alkali metal silicate in combination with the linear dialdehyde, glyoxal, as hardener for the silicate. Although safer to apply than the aforesaid silicate-formamide formulations since they generate no hazardous ammonia vapors, such silicate-glyoxal compositions oftentimes gel too rapidly for practical application particularly when used at elevated temperatures.